Tighten bounds checks in sqfs_dir_reader_reader

Use the same size check as sqfs_dir_reader_open_dir and report EOF,
even if it is possible to read the header itself, but nothing beyond
that.

Also check if it should be possible to read an entry header before
attempting and report EOF if not.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/sqfs/dir_reader.c b/lib/sqfs/dir_reader.c
index e6467ef..f560069 100644
--- a/lib/sqfs/dir_reader.c
+++ b/lib/sqfs/dir_reader.c
@@ -164,7 +164,7 @@ int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_entry_t **out)
 	int err;
 
 	if (!rd->entries) {
-		if (rd->size < sizeof(rd->hdr))
+		if (rd->size <= sizeof(rd->hdr))
 			return 1;
 
 		err = sqfs_meta_reader_read_dir_header(rd->meta_dir, &rd->hdr);
@@ -175,6 +175,12 @@ int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_entry_t **out)
 		rd->entries = rd->hdr.count + 1;
 	}
 
+	if (rd->size <= sizeof(*ent)) {
+		rd->size = 0;
+		rd->entries = 0;
+		return 1;
+	}
+
 	err = sqfs_meta_reader_read_dir_ent(rd->meta_dir, &ent);
 	if (err)
 		return err;